Refrigerating apparatus



June 13, 1944. A Q GROQMS REFRIGERATING APPARATUS Filed Feb. 5, 1941 2 Sheets-Sheet 1 June 13, 1944. A. o. GROOMS REFRIGERATING APPARATUS Filed Feb. 5, 1941 2 Sheets-Sheet 2 0 INVENTOIR. ,Zwmifiv r I have found that one of the things which limit Patented Junel3, 1944 I UNITED STATES PATENT OFFICE BEFBIGERATING APPARATUS Albert 0. Grooms, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application February 5, 1941, Serial No. 377,529

' 11 Claims; (01. zoo-s3) v This invention relates to temperature and/or the open position with the range control in a high pressure controls such as may be used for re- 7 temperature position; frigerating apparatus as well as a large variety Fig. 3 is a sectional view taken along the lines of other control applications. 3-4 of Fig. 1;

, Refrigerator control means formerly were huge cumbersome affairs which are expensive and unreliable. They have been constantly improved.

Fig. 4 is a sectional view taken along the line H of'Fig. 1; and

Fig. its a sectional view taken along the line 5-5 of Fig. 1. the improvement of refrigerator controls, par; Briefly,'I have shown in the drawings a reticularly switches,.is the use of a range spring frigerator switch which includes a bellows difor controlling the expansion of the bellows and for providing an adequate. range adjustment. Also refrigerator switches have operated the contacts through a toggle mechanism which serve as the only connection betweenthe bellows and the contacts. With such a construction the contact pressure was limited to the force'provlded .by the toggle mechanism.

It is therefore an object of my invention to provide a control which has no conventional range spring.

It is another object of my invention to provide a snap switch in which the bellows provides contact pressure directly.

It is another object of my invention to provide a control and particularly a refrigerator switch which has the following advantages:

. Simplicity Few parts A minimum of friction A low differential A wide differential adjustment Adequate range adjustment High contact pressure scription, reference being had to the accompanying drawings, wherein a preferred form ofthe present invention is clearly sho In the drawings:

Fig. 1 is a vertical sectional view through a refrigerator control embodying one form of my invention, shown in the closed position with the rang'e control in a low temperature position, to-

gether with a diagrammatic refrigerating system;

. High force to break or separate the contacts rectiy connected to the contacts. A pair of opposed toggle links act directly upon this direct connection and thereby control the movement of the direct connection to provide snap-action.

5 The differential adjustment is controlled by a ro- I tatable cam which limits the opening movement of the direct connection while the range ad- Justment is obtained by shifting the pivot point of,one of the toggle links as well as by changing my the force which tends to collapse the toggle links.

The switch is prevented from closing at the highest point of therange adjustment. The direct connection moves mainly upon one side of the dead center position of the toggle and the bellows is mainly under compression but at times may be under a slight tension when the toggle goes over the dead center position.

Referring now more particularly to the drawings, there is shown a U-shaped metal frame v member 20 which has a terminal member 22 of electrical insulating material connecting the two ends of the V-shaped frame member 20. This terminal member 22 is provided with two terminal posts I l and 28 which extend through the terminal member. The inner end of the terminal post 28 has connected thereto a bent leaf spring contact-carrying member 28 which carries the movable contact Ill. The terminal post 24 carriesthe stationary contact 32 which is electrically 4o insulated from the movable contact 30 excepting when the contacts are in closed position. Thelower end of the U-shaped member 20 has the lower end of the flexible metal bellows 34 connected thereto. This bellows 34 is connected 45 by a'capillary tube 38 to a bulb portion 38 which for' example, may be fastened in metal to metal contact. with the evaporator 40 of a refrigerating system. This system also includes a sealed metal a compressor unit", a. condenser 44 and an ex- 'pansion device "for controlling the expansion Fig.2 is a similar view of the control shown in sealed unit 42 while the other supply conductor ."Fastened to theclosedupper'end q 34, which may be reinforced, if desired, is. a metal as connected to the terminal post is while another conductor 54 connectsthe terminal post .24 to the sealed unit 42. While the switch is shown controlling a conventional refrigerating system for .the purpose ofillustrating one use thereof, the control may be used for controlling heating and other systems.-

follower member 58 provided at its lower end with a flange which may be soldered or welded 52 which receives an intermediate portion of the leaf. spring member 28. On either side of the of the bellows to the upper closed end of the bellows 84. This follower member 58 has riveted to its upper end an insulated extension 80 provided with a' slot extension 8|), the follower member is provided control may be extended in either direction for different applications without any replacement 'of parts. The toggle link 88 has its pointed end held within a small conical notch'provided upon ail-adjustable spring bar 10. This spring 10 may aschosa so as to present a higher or-lower portion of the cam 88 to the cam follower projection iill. This changes the open circuit position of the bellows follower 58 and also the open circuit position of .the toggle links 64 and 85; This of course changes the angularity of the toggle pins when the contacts are open. The further the toggle links 84 and 88 are below the deadcenter position when the contacts are in open position the greater .will be the differential. When the contacts are in the closed position the bottom of the clearance slot59 rests against the unthreaded portion 90 of the screw I4. If desired, an adlusting screw may be provided in the terminal block for adjustin'g theclosed position of the bellows follower 58.

It will be noted that the control has no range spring in the ordinary sense of the word. In

order to provide a range adjustment the spring bar 10 is bodily moved upwardly or downwardly parallel to the bellows follower 58. This moves the pivot point at. the outer end of the toggle link -88. At the same time, through the engagement of the screw I4 wih the spring bar 10; Ichange range lower I move the spring bar '10 downlikewiseha've a a series of notches above and beplacement of parts. v

This spring bar 10 has atongue 72 at its lower end which extends through an opening in the bottom or the U-shaped frame 20. This bar is actedupon by a shoulder upon the end of the threaded portion of an adjusting screw 14 threaded ns boss provided in-the wall ofth'e I U-shaped frame member 28. This spring bar III also has a tongue 16 which extends into a spiral slot l8-'which forms the cam surfaces of the cam 1 which is splined to the unthreadcd'portion of the threaded shaft 14. This threaded sh'aftl4 is provided withan' adjustable knob} 82. The spiral-slot l8 limitsthe rotation of the knob 82 to slightly under one revolution.-

. low; the normalpo'sition so: as to extend the range ofusage of the switch without the rewardly and reduce its tension. This raising 0r lowering of the range is performed by rotating the knob 82which causes thescrew 14 to be threaded inwardly or outwardly against the spring bar 10 and it also rotates simultaneously the cam 8|! so as to raise or lower the spring bar Inthis arrangement the bellows 34 acts as a very low rate spring and the change in the range,

is'chiefly the result of the change in the position and the tension of the spring bar ill causing the change in position of the toggle means relative to the movement of the bellows'follo'wer 58 and'of the bellows 34. By this construction I obtain many advantages not found in prior controls. The switch is simple and has very few The shaft 14, for the purpose ofzproviding a proper support, extends to the Opposite vleg of the U-shaped frame member 20 which is provided with a bearing on the opposite side for this Purpose. However, upon this opposite side of the control, an unthreaded portion 80 of the threaded shaft 14 telescopes within a cam shaft 92 which provides a bearing support and the cam shaft 92 in turn is rotatively mounted in the bearing 85 provided by extruding a flange from the side wall of the U-shaped frame member 20.

The follower 58 is provided with an elongated aperturefor providing clearance around the shaft portion of the threadedshaft 'I4. Upon the outside of the frame member- 20, the cam shaft 82 1s provided with a screwdriver slot 94 anda; lock-nut 88 or'some other' suitable look.- ing device. The cam shaft 82 at its inner end is v provided with ,a spiral cam 98, located in the .path'of a follower projection lili which is struck out from the bellows follower 58. This follower projection lill strikes and rests upon the differential cam 98 ,when the switch contacts are moved to the open position. The (inferential adjustment is made by rotating the cam 98 by a screw driver or similar device engaging the outer end of the cam shaft 92 jhasa direct connection with the movable con-' tact 38 through the bellows follower 58-so that the force provided by the pressure within .the bellows can be exerted directly through the spring. contact-carrying member 28 to hold the contact '88 tightly closed, while the spring force of the bellows 34 together with any vacuum which may be present within the bellows may aid the toggle mechanism in pulling the contacts apart. I prefer to charge the bulb and -the bellows 34 with a limited charge of sulphur dioxide since that gas is substantially at atmos-- phericpressure within the normal range of operation in a household refrigerator switch. However, limited charges of other volatile liquids may be used for this and other applications and other types of fluids may be used for operating methyl chloride may be used for low temperature applications such as ice cream cabinets.

This switch can be readily made with a much '1 lower diiferential than has been heretofore feasible in household refrigerator controls. In spite of the low differential no difficulty is encountered in obtaining an adequate range adjustment beassaoss ment, namely by shifting the position of the toggle mechanism; Theoretically, a spring bar, such as the spring bar 10, should beprovided .upon both sides of the control with one bar for the outer end of each'togglepin. While slightly better results could be obtained by such a construction I find that the increased complication required by such a construction is not warranted by any possible improvements in results excepting possibly in unusual situations. I find that altogether satisfactory results are obtained by the construction shown.

The control operates to the greater extent below the center line of the toggle links H and 66. In'the lower portions of the range adjustment I prefer to allow the toggle pins to go slightly across the dead center, as shown in Fig. 1. For another positions I prefer to operate altogether upon the lower side of theshown in Fig. 2. In the highest position of the range adjustment, th opening force is so great that the switch with the limited charge provided will not open at room temperatures to provide a shut-oil. I make the rate of the spring bar itself sufiiciently low so that the resultant toggle components are high enough that the force required to move the bellows follower upwardly from'the open circuit position is greatest at the start of the movement so that when the movedead center position, as

ment starts it will go directly to completion at an accelerating speed so that the contacts and-32 are moved rapidly to closed position. Upon the return movement, the contacts are opened with a similar snap action. In addition, the slot 62 is made sufficiently large so that there is som lost motion between the insulated member 60 and the spring contact-carrying member 28. When the contacts are in the closed position the bottom of the slot 62 bears heavily upon the spring contact- 58 moves downwardly the top of the slot 62 does not engage the spring contact-carrying member 28 until the bellows follower has begun to move downwardly at an accelerating speed. This pro- Jl carrying member 28. When the bellows follower another position to cause the limits of movement to extend to opposite sides of the dead center position 01' the toggle means.

2. A control comprising an actuating means, a

toggle means connected to the actuating means for controlling the movement of the actuating means, adjustment means eii'ective in one posi tion for setting the termination of movement of the actuating means in one direction directly adjacent One side of the dead center position of the toggle means and efiective in a second position for terminating the movement in the same direction directly adjacent the opposite side of the dead center position of the toggle means, and means for'varying the termination of the movement in the opposite direction for varying the differential of the control.

3. A control comprising an actuating means, a switch contact device, positive connecting means providing a positive connection between said means and said device for moving said switch contact device in substantially direct proportion .to the'movement of the actuating means for applying a positive contact closing force to said device, and toggle means for controlling the movement of one of said means.

4. A control comprisin an actuating means, a switch contact device, positive connectin means providing a .positive connection between said means and said device for moving said switch contact device in substantially direct proportion to the movement of the actuating means for applying a positive contact closing force to said device, toggle means for controlling the movement of one of said means, and adjustment means for vary ing the dead center position of the toggle means in the direction of movement of one of the other vides a very desirable form of snap action which prevents unnecessary arcing and the burning or the contacts. For use with direct current, a blow out permanent magnet may be used to snuiT out any arc at the contacts.

There is substantially no friction in the switch since the only pivot points are those of the toggle links 64 and 66 which are formed by knife'edges. There is substantially no friction between the insulating extension carrying member 28 and the spring effect of the bellows 34 and the contact-carrying spring memand the spring contact-- her 28 is comparatively low. By this new type of switch construction, I therefore obtain many advantageous features. Y

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope oi the claims which follow.

What is claimed is as follows:

'1. A control comprising an actuating means,

I toggle means connected to the actuating means,

a control device operated by one of said means, and adjustment means for varyingthe movement ol' the actuating means and the toggle means said adjustment means including means effective in one position to cause the movement of said toggle means to be confined to one side of the dead center position of the toggle means, and'en'ective in means.

5. A control comprising actuating means, a control device movable to first and second control positions, positive connecting means positively connecting said actuating means and said control device for moving said control device in substantially direct proportion to the movement of said actuating means, a support means, adjustable means for moving said support means generally parallel to the movement of said connecting means, and toggle means connecting said support means and said connecting means for controlling I 50' the movement of the connecting means.

6. A control comprising actuatin means, a control device movable to first and second control positions, positive connecting means positively connecting said actuating means and said control device for moving said control device insubstantially direct proportion to the movement of said actuating means, a support means, adjustable means for moving said support means generally parallel to the movement of said connecting means, a toggle link linking said connecting means and said support means, said support means incorporating spring means for applying a column load to the toggle link.

7. A control comprising actuating means, a

control device movable to first and second control tially direct proportion to the movement of said actuating means, a support means, adjustable means for moving said support means generally parallel to the movement of said connecting means, a toggle link linking said connecting means and said support means, said support means for applying a' column load to the toggle link, and means for varying the tension of said spring means.

8. \A control comprising actuating means, a, control device movable to'first and second control positions, positive connecting means positively connecting said actuating means and said control device for moving said control device in substantially' direct proportion to the movement of said actuating means, a toggle means having one end pivoted to one of said means, and a spring means pivotally connected to said toggle means.

asoaoae v tially-direct'proportion to the movement of said,

actuating means, a pair of toggle links extending on opposite sides of and each being pivotally connected at one end to one oi saidmeans, an an- 9. A- control comprising actuating means, a I

control device movable to first and second control positions, positive connecting means positively connecting said actuating means and said control device for moving said control device in substantially direct proportion to the movement of said actuating means, a toggle means having one end pivoted to one of said means,,a spring means pivotally connected to said toggle means, and means for adjusting said spring means.

10. A control comprising actuating means, a

control device movable tofirst and second control positions, positive connecting means positively connecting said actuating means and said control device for moving said control device in sumtantially direct proportion to the movement of said chorage for the other end of each of said toggle links, and adjustment means for adjusting one of said anchorages in a direction generally parallel to the movement of said one means.

14. A control comprising an actuating means, a switch contact device, positive connecting means extending directly between the actuating means and. the switch contact device for positively providing a movement of the switch contact device substantially in proportion to the movementioi' the actuating means and for applying a, positive contact closing force to said contact device, a toe gle means for controlling the movement of one of said means, and an adjustable stop for limiti m the movement oi said connecting means intone direction.

15. A control comprising an actuatingmeana.

a control device operated by said actuating means,

. a toggle link connected to once? said means, a

actuating means, a toggle means having one end pivoted to one of said means,and adjustment means for moving. the other end of the toggle means. a

11. A control comprising actuating means, a

- switch contact device movable to first and second control positions, positive connecting means positively connecting said actuating means and said switch contact device for moving said switch contact device in substantially direct proportion to.

connecting said actuating means and said control device for moving said control device in substantially direct proportion to the movement of said actuating means, a pair of toggle links extending on opposite sides of and each being pivotally connected at one end to one of said means, a spring means for applying a column load to said links, and adjustment means for moving the other end 'of one of said toggle links.

, 13. A control comprising actuating means, a control device movable to first and second control positions, positive connecting means positively connecting said actuating means and said control device-for'moving said control device in substanflat spring bar connected to and exerting a yielding force upon the end of said toggle link for providlng' a snap action, and adjusting means for moving the spring bar relative to one or said means in a direction transverse to said toggle link for-varying the tripping point 01 said link.

16. A control comprising an actuating means,

a control-device movable to first and second con trol positions, a'positive two way constant ratio power transmitting connecting means connecting said actuating means and said control device for positively operating said control device to and from both said first and second control positions in movements every part of which is substantially in a constant ratio to the movement of the actuating' means, and toggle means-having its greatest resistance to movement at the beginning of the movement of the control'device from its first and second control positions and providing ,an acceleration of the movement as the movement progresses for controlling the movement of one of said means, said toggle ineans including a substantially rigid link and a low rate spring having a small change in force for the amount of deflection caused by the movement of the link.

' 17. A control comprising a control means movable to first and second control positions, an actuating means operably connected to the control means for moving the control means to and from said positions, toggle means for controlling the movement of one of said means to provide a snap acting movement, 'said toggle means including .a-

toggle spring, adjustment means for directly adlusting the tension oi'said toggle spring, and adjustment means for adjusting the dad'center position of the toggle means.

; ALBERT o. GROOMS. 

